Generally, a wireless local area network (WLAN) includes a plurality fixed and mobile devices configured to communicate with one another using radios. Such WLANs may be referred to, for example, as Wi-Fi networks. Further, such WLANs may use an IEEE 802.11 communication protocol (e.g., 802.11a, 802.11b. 802.11g, 802.11n). Artisans will recognize from the disclosure herein that other protocols for wireless and/or wired communications may also be used.
Current techniques for determining a location of a mobile device in a WLAN include using a Global Positioning System (GPS), Wi-Fi Time Difference of Arrival (TDOA), and Wireless Access Point Wardriving.
In addition to providing navigation within the urban core, GPS is widely used to aid navigation worldwide. GPS was originally designed as a military system and has had recent broad adoption for civil and civilian uses due to its inherent accuracy and a strong history of reliable performance. Several other entities, including the European Union, Russia, India, China, and Japan have satellite-based Position, Navigation, and Timing. Collectively, the use of satellite-based navigation services is referred to a Global Navigation Satellite Systems (GNSS). GPS, however, remains the de facto system of choice, primarily because of its maturity, with over fifteen years of reliable free service. GPS acceptance has also been enhanced by open interface control documentation (ICD), which allows receiver manufacturers to confidently design systems against a reliable standard.
Because GNSS systems are satellite-based, however, there is a danger that either natural or human threats to these systems could make them vulnerable to outages. Further, other locating systems may not provide a desired level of accuracy or may be overly expensive.